The present invention relates to an electrical storage cell battery, of the type comprised of electrically interconnected cells, each cell housing positive and negative plates, intermediate separators and electrolyte of the free or immobilized type.
The battery of the invention is preferably a lead-acid battery, of the type used, among other applications, for start-up, illumination and semi-traction of automobiles.
More specifically, the battery of the invention relates generically to a conventional type storage cell, also known as flooded, or to a gas recombination type cell with gas outlet controlled by a valve, also known as an immobilized electrolyte storage cell, as the electrolyte is embedded in a glass fiber separator or is in the form of a gel.
The trend in automobile manufacturing is evolving towards increasingly complex equipment which require greater power. Thus, batteries must be more powerful and resistant to charge and discharge cycles, in order to ensure start-up.
It is standard practice to manufacture batteries rated at twelve volts. In order to fulfil higher power requirements, an increase in the voltage to 36 volts is being considered. However, although a simple series connection of three 12 volt batteries would provide the 36 volts, the space occupied by three such batteries would be three times greater than that for a single one. In addition, electrical connections must be sufficiently reliable and of a length and section such that resistance caused voltage loss is minimal. Furthermore, both the mechanical and electrical connections should be sturdy enough to withstand the vibrations suffered by the vehicle, particularly when traveling on uneven ground.
Additionally, current 12 volt batteries have their various cells back to back to each other, resulting in significant cooling differences in the cells. Thus, as the battery is warmed by the heat lost by the engine, certain cells undergo a much higher temperature rise than others which are better refrigerated. Cells that are at a higher temperature will suffer a greater evaporation rate of the water in which the electrolyte acid is dissolved, so that the electrolyte concentration will become higher. Furthermore, the higher is the temperature, the greater is the load current, and the greater the over current, causing a decomposition of the electrolyte water, further contributing to the increase in electrolyte concentration. The greater is the electrolyte concentration the greater will be the battery deterioration, not only due to the chemical attack on the active materials and the grids but as the electrolyte water content decreases, the level on the plates falls and eventually the plates may not be covered, resulting in permanent damage to plates, welding and separators. This damages both battery operation and lifetime.
These refrigeration problems are considerably increased when three current type 12 volt batteries are joined to obtain 36 volts.
The object of the present invention is to solve the aforementioned problems with a battery of the type described above, constructed to allow optimum refrigeration of the various cells and that is provided with means for connection to other batteries, in order to obtain sets which multiply the rated voltage, without reducing the refrigeration capacity of the cells.
The battery of the invention has the advantage, as compared with traditional batteries, of having a refrigeration area for each cell which ensures that the cell temperature is never too high nor different from the temperature of the other cells. Additionally, the solution proposed by the invention for mechanical attachment between two or more batteries as well as for their electrical connection allows to obtain sets which may withstand vehicle vibrations without being harmed, even when the vehicle is traveling on uneven ground. All of this causes increased performance and lifetime of the battery of the invention.
A further object of the invention is to provide a battery with an external configuration allowing connection of two or more batteries in several positions, so that a set is obtained with a geometry and arrangement which can be adapted to the space available for installation in each case.
The battery of the invention comprises electrically interconnected cells, each of which is provided with elements which comprise positive plates, negative plates, intermediate separators and free or immobilized electrolyte.
The positive and negative plates which make up the electrodes are of the pasted type, and plates of like polarity are separated from the opposite plates by a separator, which may be porous or preferably of glass micro fiber. These positive and negative plates are preferably wound in a spiral.
Electrical connections between the various elements of different cells consist of automatic fusion welding in a mold or COS welding. The electrical connection is preferably shaped as an Omega.
Each cell is further contained in an independent cylinder, with all the vessels of a battery placed in parallel, in a same plane, either next to or tangent to each other, so that there are longitudinal spaces between the cylinders which ensure uniform refrigeration, thereby avoiding temperature differences between the cells.
Each of these cylinders is connected to the others forming a battery with an open top on the bottom of a preferably rectangular prismatic vessel. The vessel is externally provided on its sides with complementary means of attachment to other vessels. These mechanical attachment means are preferably male and female elements which couple to each other and are provided on at least two opposing sides of the vessel.
The mechanical connection means allow joining of two or more batteries with their vessels touching or near each other, but with longitudinal cooing spaces left between the cell cylinders.
In order to improve the connection between batteries, the invention includes complementary means on the cell cylinders on diametrically opposing positions, so that the batteries are joined by the vessel connection means and the cylindrical cell means.
Preferably, the male and female elements of the battery mechanical connection means have a dovetail configuration, so that they may be joined by relative displacement of the batteries to be connected.
There is a vessel at the upper end of the cell cylinders of a given battery. The vessel has internal transverse partitions generally at the spaces between the cells. the partitions all have an upper central groove for passage of the electrical connection bridges between adjacent cells.
The open top part of the prismatic vessel is closed with a prismatic lid provided with filling orifices placed opposite each cell, in order to allow formation or first charge. The ends of the lid contain embedded cold-stamped bushings which are later welded to the terminals of the end cells to form the corresponding positive and negative terminals.
The lid is also provided with an orifice meant to house a valve. The valve is a cylindrical cap made of a special elastomer, which ensures outlet of gases to the exterior but which prevents their entry.
The end sides of the lid have air passage ducts which allow an effective cell refrigeration when several cells are joined.
A prismatic cover is on top of the lid in order to seal it from the outside. The cover is provided on its inside with a first circular flange which communicates with a centralized gas outlet tube provided in the center of one of the cover sides. A second circular flange is also provided which matches the housing of the elastomer valve to ensure that the valve remains in its position and that gas outlet can only take place through its sides. The cover is preferably provided with a number of flanges matching the filling orifices of the lid in order to close them.
A microporous plastic element, such as a vyon pill, known in this field because it channel all gases which may be emitted by the battery towards the outlet tube, is placed inside the first cover flange. This microporous element allows gas outlet by diffusion through its pores, acting as a flame trap system so that if any sparks ignite the hydrogen emitted by the battery when it is charging, that element would prevent the flames from entering the cells.
The electrical series connection of the batteries is performed with a connector, which preferably consists of a metal bridge ending in two clamps adaptable to the size of the corresponding terminal. The clamps are tightened with butterfly nuts which press on the terminal when tightened, providing a reliable and highly vibration-resistant connection.
A more detailed description of the invention appears below with reference to the accompanying drawings relating to embodiments of the invention shown for purposes of illustration only and not meant as a definition of its limits.